James P. Hanna

Peer-to-peer communications for tactical environments: Observations, requirements, and experiences

Tactical edge networks present extremely challenging environments for communications given their wireless ad hoc nature and the inherent node mobility. Military applications such as Blue Force Tracking, inter-team communications, remote unmanned vehicle control, and sensor data mining/fusion thus have to deal with unstable links with limited bandwidth and variable latency. The peculiar characteristics of tactical networks call for peer-to-peer approaches to realize complex, adaptive, and fault-tolerant applications to be deployed in the battlefield. This article reports on our observations from several tactical networking experiments in which we have deployed state-of-the-art applications and services that leverage P2P communications. More specifically, we discuss why P2P approaches are critical for tactical network environments and applications. We then analyze the requirements that should be satisfied by P2P middleware for tactical environments. Finally, we discuss a case study, the Agile Computing Middleware, and present experimental results that demonstrate its effectiveness.

Communications middleware for tactical environments: Observations, experiences, and lessons learned

Tactical networking environments present significant challenges that must be overcome in order to effectively support net-centric warfare. The wireless and ad hoc nature of these networks implies unreliable connectivity, limited bandwidth, and variable latency. Past and current research has focused on physical and data link layers, routing protocols, transport protocols, and cross-layer aspects. However, significant work is needed at the upper layers to better support application requirements. In our experience, achieving effective communications in tactical environments requires taking into account application requirements and communication patterns, designing a rich interface between the application and communication layers, and realizing a communications middleware specifically adapted to tactical networks. In this article, we report on our observations from several tactical networking experiments and demonstrations and the lessons learned from deployment of the Mockets middleware to support tactical communications. We hope these experiences are useful to others designing and implementing applications and systems for tactical environments.

Integrated information and network management for end-to-end Quality of Service

Publish-subscribe-based Information Management (IM) services provide a key enabling technology for net-centric operations. This paper describes technology for Quality of Service (QoS) and Internet-Protocol-based Airborne Networking features for IM services. Enhancing IM services with airborne networking features improves effectiveness in combined tactical and enterprise networks with mobile airborne and ground-based embedded platforms interacting with enterprise systems in command and control operations.

Dynamic resource allocation in an HPC environment

Analysts within the military strategic planning process need to be able to anticipate and respond in real-time to a dynamically changing battle space with counter actions. The capability is required to accept current information into a simulation and rapidly peer into the future at any given moment to derive hypotheses about future alternatives. It is virtually impossible to identify or predict the specific details of what might transpire. Our research interest is to develop techniques to assess potential courses of action (COAs) against the adversarial environment. Utilizing HPC technology, multiple force structure simulations can be dynamically executed in parallel to concurrently evaluate the hypothesis of assessing a given COA against a range of adversarial eCOAs. The uncertainty of the adversary decision process requires simulation capabilities that spawn multiple simulations from critical decision points to evaluate alternative eCOAs. The focus of this paper is on the development of a simulation framework that provides the foundation for faster than real-time parallel COA simulations. Within this framework is a requirement to be able to dynamically allocate and reallocate resources in an HPC environment. The authors describe techniques to clone and create variant simulations in real-time and the dynamic system requirements and use of HPC nodes.

A cross-layer communications substrate for tactical Information Management Systems

In this paper we introduce XLayer, a cross-layer communications substrate for tactical Information Management Systems which enable nodes on a radio network to seamlessly communicate with nodes on different heterogeneous networks. While conventional cross-layer strategies for tactical environments tend to focus on the localized optimization between neighbor layers of the communications stack, our approach focuses on the interface between middleware and the underlying communications infrastructure. The XLayer communications substrate leverages native information and services available at the tactical communications infrastructure to improve the functionally and capabilities of overlay applications and middleware. The XLayer also provides the necessary interfaces and mechanisms to enable application-driven requirements to parameterize and regulate the operation of the underlying communications infrastructure. After a brief description of the target environment and system requirements we will introduce the proposed design for the cross-layer communications substrate, highlighting specialized controllers and adaptors for communication interfaces and tactical radios. We will then introduce new cross-layer strategies for discovery, routing and transport targeted to Information Management System (IMS)-support, followed by our NS-2 simulation results, analysis, and conclusions.

A dynamic and policy-controlled approach to federating information systems

Timely access to relevant data and information is critical to successful mission execution in network centric warfare. Often, the data required to support a mission is not always resident within a single system, but is distributed among multiple systems that must be dynamically interconnected to support the data and information needs. While proprietary and stove-piped information systems have slowly given way to standardized information management architectures (such as the Joint Battlespace Infosphere (JBI) architecture developed by the US Air Force Research Laboratory), each independent organization and/or mission is normally associated with a separate instance of a managed information space that operates in an independent manner. This is necessary given the different stakeholders and administrative domains responsible for the information. However, the demands for coordination and cooperation require interoperability and information exchange between these independently operating information spaces. This paper describes a federated approach to interconnecting multiple information spaces to enable data interchange. We propose a set of interfaces to facilitate dynamic, runtime discovery and federation of information spaces. We also integrate with the KAoS policy and domain services framework to realize policy-based control over the federation and exchange of information. Our approach allows clients to transparently perform publish, subscribe, and query operations across all the federated information spaces. We have integrated with three existing JBI implementations – Apollo from the Air Force Research Laboratory, Mercury from General Dynamics and AIMS from Northrop Grumman. Most recently, we have integrated with Phoenix, a fully SoA (Service-oriented Architecture) based approach to information management.

Improving timeliness and reliability of data delivery in tactical wireless environments with Mockets communications library

Network centric warfare relies on the timely and reliable delivery of data to disparate cooperating nodes in tactical networking environments. Given the limited bandwidth available and the unreliability of network links, data often accumulates in application and/or network queues, resulting in increased latency in the delivery of the data. The Mockets communications library addresses this problem via dynamic message replacement. The message replacement functionality of Mockets allows the system to drop all but the most recent message within a specific message flow by removing older, outdated messages from the queues. This paper describes and evaluates, in the context of the U.S. Air Forces Joint Battlespace Infosphere (JBI) system, the timeliness of end-to-end delivery of data using the Mockets library. In addition to dynamic message replacement, other capabilities in the Mockets library include options for reliable vs. unreliable and sequenced vs. unsequenced delivery of data, detailed statistics and feedback regarding the connection, and assignment and dynamic adjustment of priorities of messages. This paper provides a qualitative analysis of these different capabilities and their suitability to address the transport requirements in JBI. It also provides a quantitative comparison of Mockets with SCTP and SCPS-TP, which are similar technologies with existing available candidate implementations. Our results show that the Mockets library with the message replacement significantly outperforms these other transport protocols.

An Aspect-Oriented Approach to Assessing Fault Tolerance

Fault tolerance and survivability are important aspects of many business-critical and mission-critical systems but it is still difficult to assess how well fault tolerance techniques work. Ensuring fault tolerance in military communication systems is particularly important due to the inevitability of hardware failure, data corruption, or service interruption and the risk that cascading failures could jeopardize critical military operations. In this paper, we present a fault tolerance assessment framework designed for distributed systems that provides automated injection of faults without changes to client or server code and automated assessment of whether the injected faults are tolerated. The framework applies aspect-oriented programming, specifically AspectJ, to inject faults and weave in assessment criteria. The framework supports both assessing the tolerance of direct faults, such as crashes and corruption, like traditional fault injectors, and conditional faults, which can be probabilistically, randomly, or periodically injected at runtime. This latter class of faults is not historically supported by fault injectors, but enables the assessment of tolerance to many important classes of faults threatening modern distributed military communication systems, including timing faults, resource exhaustion (e.g., Denial-of-service), and integrity faults that are traditionally difficult to tolerate and assess. Additionally, the framework provides a centralized view for users enabling them to monitor and script coordinated tests comprising performance metrics and injected faults spanning services, applications, and hosts.

Knowledge-Based Approaches to Information Management in Coalition Environments

The community of interest information-sharing model lets coalition partners publish and disseminate data in a controlled fashion. In this vein, the authors have extended the Phoenix information management system to improve document selection and filtering.

Simulating Effects Based Operations

Effects based operations (EBO) are proving to be a vital part of current concepts of operations in military missions and consequently need to be an integral part of current generation wargames. EBO is an approach to planning, executing and assessing military operations that focuses on obtaining a desired strategic outcome or “effect” on the adversary instead of merely attacking targets or simply dealing with objectives. Alternatively, the emphasis of conventional wargames is focused on attrition based modeling and is incapable of assessing effects and their contribution to the overall mission objectives. The focus of this paper is the integration of an EBO modeling scheme [1] within a force-on-force simulator. In this paper, the authors review the EBO modeling capability and describe its’ integration within the wargame; including the integration of center of gravity (COG) models, the realization of indirect and cascading effects, the impact of the COG models on simulation control files, and the use of COG models to link the simulation commander with assets. A simple scenario demonstrating indirect and cascading effects is described and the results are presented.